Chute for Laser Sintering Systems

ABSTRACT

There is provided improved laser sintering systems that increase the powder density and reduce anomalies of the powder layers that are sintered, that measure the laser power within the build chamber for automatic calibration during a build process, that deposit powder into the build chamber through a chute to minimize dusting, and that scrubs the air and cools the radiant heaters with recirculated scrubbed air. The improvements enable the laser sintering systems to make parts that are of higher and more consistent quality, precision, and strength, while enabling the user of the laser sintering systems to reuse greater proportions of previously used but unsintered powder.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority pursuant to 35 U.S.C. 119(e) toU.S. Provisional Application Ser. No. 61/793,870, filed Mar. 15, 2013.

FIELD OF THE INVENTION

The present invention is related to laser sintering systems, and moreparticularly, to laser sintering systems apparatus and methods forimproving part quality and reduced disposal of used, unsintered powder.

BACKGROUND OF THE INVENTION

Laser sintering is one form of additive manufacturing that fabricatesthree-dimensional objects from digital data. As known in the art, lasersintering heats layers of powder, typically a polymer or a metal, with alaser to cause the powder particles to fuse to one another inpredetermined patterns to define the cross-sectional layers of theobject being fabricated. Such techniques are disclosed in U.S. Pat. Nos.4,863,538; 5,155,321; 5,252,264; 5,352,405; 6,815,636; 7,569,174; and7,807,947, the disclosures of which are incorporated by reference hereinin their entirety.

One problem with laser sintering is laser attenuation during the buildprocess whereby the laser power at the image plane (the surface of thesinterable powder being exposed to the laser beam) changes (typicallydecreases). Such change in laser power may be due to a number of issuesand can lead to parts being different colors from the bottom to the top(along the z-axis) or having different mechanical properties along thez-axis.

Another problem with laser sintering, particularly with polymers thatare heated to near the melting temperature, is that the sinterablepowder that is not fused can be reused only a certain number of timesbefore the powder produces parts with undesirable quality (such as“orange peeling” on the surface), coloration, or reduced mechanicalproperties. The result is that operators of laser sintering machinesmust dispose of a certain amount of used laser sintering powder tomaintain part quality.

BRIEF SUMMARY OF THE INVENTION

The various embodiments of the present invention address the above needsand achieve other advantages that improve the part quality and reducethe need to dispose of sinterable powder. One embodiment of the presentinvention includes methods for applying the powder layer to reduce thelikelihood of surface features that can lead to reduced part strength oraccuracy and that improve the density of the powder in the layer.Certain embodiments use a “two pass” approach (also called “dual APL”(APL=Apply Powder Layer)) to laying down a single layer of powder (witha counter-rotating roller or other powder distributing device) bydistributing a layer of powder in a first pass similar to traditional(prior art) applications of a powder layer, but then, unlike the priorart, the roller is moved back in a second pass that distributes residualpowder to fill gaps and level the surface of the powder layer. In orderto distribute the residual powder from the first pass, a return powderdevice (such as a piston) is provided on an opposite side of the partbed (the area where the powder is laser sintered) from where the powderis deposited by a hopper. The return powder device is lowered to allowthe residual powder to pass beneath the roller and is raised after theroller has passed so that the roller can distribute the residual powder.Any residual powder that remains after the second pass is deposited intoa powder return shoot on the side of the part bed. By using the two passtechnique, the powder layers have improved uniformity and betterdensification for more accurate laser sintering.

Further embodiments of the present invention include a laser powermeasurement device that is able to measure laser power within the buildchamber. Typical laser sintering systems do not include laser powermeasurement devices (measurements are simply done during service by aserviceperson) or the laser power is measure prior to the laser beamentering the build chamber. The build chamber of a laser sinteringsystem is typically very hot and includes fumes and dust that canadversely affect surfaces. The present invention provides a laser powermeasurement device that is within the build chamber to determine thelaser power delivered to the powder layers in order to adjust or controlthe scan speed and/or other parameters to ensure that the power beingdelivered to the sinterable powder is consistent to avoid degradation orother changes in part quality or accuracy. In some embodiments, thelaser power measurement device is positioned below the laser window(typically on the ceiling of the build chamber through which the laserenters the build chamber), but above the heaters that heat thesinterable powder (primarily by radiation) so that the device does notblock heat delivered to the powder and/or become overheated. By havingthe laser power measurement device removed as much as possible from theimage plane upon which the laser beam is focused, the laser is lessfocused and the sensing device is better able to withstand the laserwithout being adversely affected by the laser. In some embodiments, thelaser power measurement device comprises a movable mirror that isextended from a position outside the laser scanning area into a positionwhere the laser can be directed to the mirror to direct the laser to thesensing device. Once the measurement has been taken, the mirror can beretracted out of the way of the laser. In some embodiments, the laserpower measurements are taken during the application of a new powderlayer so that the build time for the part(s) is not increased. Infurther embodiments, the laser power measurement device is a sensor on amovable (such as rotatable) arm that may be selectively positioned forthe laser to project directly onto it.

Still further embodiments of the present invention include a chutedevice for the deposition of powder between the roller and part bed withlittle or no dust being created. The chute device of certain embodimentsis a rigid slot below the hopper that extends to near the surface thepowder is being deposited to minimize the distance the powder must fall,thus minimizing the amount of dust created. The chute device isrotatable so that it does not interfere with the movement of the roller.The chute is also positioned so that it does not block the laser beamfrom the part bed. In some embodiments, the chute includes heaterelements to preheat the powder to be deposited.

Other embodiments of the present invention include a roller heaterpositioned below or proximate the stationary roller position (where theroller is parked during the laser scanning operation) so that the rollersurface may be heated to a desired temperature. The roller heater mayalternatively comprise a chute heater that pre-heats powder in the chuteand also heats the roller surface. The roller may be rotated so that theroller heater evenly heats the surface of the roller to preventtemperature gradients on the roller surface which can lead toundesirable adhesion of powder to some, but not all, surfaces of theroller which results in powder being slung behind the roller whichfurther results in uneven powder surfaces that ultimately result inrough surfaces or other imperfections in the final part.

Still further embodiments of the present invention include an airscrubber that cleans the air (consisting primarily of nitrogen) withinthe build chamber. The air is cooled through the scrubber to assist withthe removal of airborne contaminants by the filter(s). The exhaust airof the scrubber that is recirculated back into the build chamber isexhausted into a heater bracket that retains the heaters (that heat thepowder by radiation and convection) in order to (i) reheat therelatively cool recirculated air and (ii) cool the heater brackets andheaters so that the heaters are not overheated. The heater brackets haveexhaust holes along an outwardly facing surface so that the air iscirculated back into the chamber in a way that does not createsignificant turbulence or other undesirable air flow that couldadversely affect the laser sintering process. Therefore, the variousembodiments of the present invention provide significant improvements tothe laser sintering system and process that result in improved partquality and reduced waste material.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale and are meant to be illustrative and not limiting, and wherein:

FIG. 1 is a perspective view of a laser sintering system in accordancewith one embodiment of the present invention;

FIG. 2 is a side cross-sectional view of the laser sintering system ofFIG. 1;

FIG. 3A is an enlarged side cross-sectional view of the roller, hopper,chute, roller heater, and other portions of the laser sintering systemof FIG. 1, wherein the chute is in the down position;

FIG. 3B is an enlarged side cross-sectional view of the roller, hopper,chute, roller heater, and other portions of the laser sintering systemof FIG. 1, wherein the chute is in the up position;

FIG. 4A is an enlarged perspective view of the hopper and chute of theembodiment of FIG. 1, wherein the chute is in the down position;

FIG. 4B is an enlarged perspective view of the hopper and chute of theembodiment of FIG. 1, wherein the chute is in the up position;

FIG. 5A is a side cross-sectional view of the upper portion of the lasersintering system of FIG. 1, showing the laser power measurement devicein the retracted position;

FIG. 5B is a side cross-sectional view of the upper portion of the lasersintering system of FIG. 1, showing the laser power measurement devicein the extended position;

FIGS. 6A-6C are enlarged perspective views of the laser powermeasurement device (in the extended position) of a further embodiment ofthe present invention, wherein the mirror of the laser power measurementdevice includes a telescoping tube that protrudes into the build chamberthrough a sealed opening below the laser window (not shown);

FIG. 7A is an enlarged perspective view of a scrubber of the lasersintering system of FIG. 1 showing the internal passages and filters ofthe scrubber, as well as the check valve on top and blower motor on theside;

FIG. 7B is an enlarged side view of the scrubber of FIG. 7A showing thesingle scrubber inlet and the dual scrubber outlets (each outlet is influid communication with one heater bracket);

FIG. 7C is an enlarged perspective view of the scrubber of FIG. 7Ashowing the scrubber inlet and scrubber outlets and the heat sink andfan for cooling of the air to be scrubbed (filtered);

FIG. 8 is an enlarged perspective view of the laser sintering system ofFIG. 1 showing the heater brackets (yellow) through which the cooled airfrom the scrubber outlets is reintroduced into the build chamber inorder to heat the air (using the waste heat of the heaters) and to helpcool the heaters; also shown is the piping/duct connecting the scrubberinlet to the opening in the build chamber above the heater brackets;

FIG. 9 is an enlarged perspective view of the laser sintering system ofFIG. 1 showing the heaters and heater brackets and the passages on thesides of the heater bracket for the pre-heated air to flow into thebuild chamber in a direction that does not adversely affect the powderlayers; and

FIG. 10 is an enlarged perspective view of the laser sintering system ofFIG. 1 showing the return powder device in the raised position, whereinthe return powder device is on an opposite side of the part bed from thehopper and chute.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, the invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Although apparatus and methods for providing improved partquality and reduced powder disposal are described and shown in theaccompanying drawings with regard to specific types of laser sinteringsystems, it is envisioned that the functionality of the variousapparatus and methods may be applied to any now known or hereafterdevised powder fusing systems in which it is desired to created threedimensional objects (parts) out of powder based upon digital datarepresenting the part to be made. Like numbers refer to like elementsthroughout.

With reference to FIGS. 1-10, laser sintering systems in accordance withembodiments of the present invention are illustrated that include manynovel upgrades to prior art laser sintering systems that increase partquality and reduce powder disposal. These inventions not previous knownor used in the art provide significant improvement to the part qualityby providing consistent energy delivery to the sinterable powder so thatthe material properties are improved and consistent throughout the partin all directions (x-axis (side to side in the build chamber), y-axis(front to back in the build chamber), and z-axis (bottom to top in thebuild chamber)). Moreover, the inventions, in particular those relatingto the dual APL, provide powder layers of improved density and with noor minimum peaks, valleys, or voids that provide better flow control oflaser sintered particles that enables the creation of more accurate,stronger parts and enables powder to be reused (the powder used in alaser sintering build process but not sintered) for many more buildprocesses, thus significantly reducing the need for virgin powder(new/fresh powder that has not undergone a build process) and the needto dispose of used powder. Therefore, the present inventionssignificantly reduces the costs associated with laser sintering ofparts, which makes parts made by laser sintering more affordable, andultimately results in laser sintering becoming more competitive againstparts made by other additive manufacturing techniques, subtractivemanufacturing techniques, and other traditional manufacturingtechniques.

The illustrated embodiments are designed for polymer systems that usepolyamide powders or PEEK powders or other polymer powders; however,other embodiments of the present invention may be used with furthermaterials such as metals, composites, ceramics, and any other powdermaterials used to form three-dimensional objects from digital data.

Turning now to the embodiment of FIG. 1, the laser sintering system 10includes a build chamber 12, a removable part bed cart 14, and a laserassembly 16 that includes the laser, scanning mirrors and other opticssimilar to prior art laser sintering systems. The laser sintering system10 also includes a control panel 18 or other user interface, such as atouch screen computer or tablet, for the operator to control and/ormonitor the laser sintering system. FIG. 1 also shows portions of thelaser sintering system 10 that are not inside the build chamber 12, suchas the powder hopper 20, from which powder is supplied to the buildchamber, and the scrubber 22 that cleans and recirculates the air(primarily nitrogen) in the build chamber.

FIG. 2 is a cross-section of the laser sintering system that illustratesadditional features of the system, both inside and outside the buildchamber 12. The return powder receptacle 24 receives powder that is notused during the dual APL process. Powder (not shown) deposited into thereturn powder receptacle 24 can be stored for later use in a subsequentbuild process or recirculated automatically back to the hopper 20 foruse in the same or subsequent build process. FIG. 2 also illustratescomponents and systems within the build chamber 12 such as the roller26, the chute 28, the image plane 30 where the powder layer is lasersintered (the top layer of the part bed 31), and the return powderdevice 32 (also shown in FIG. 10), which in the illustrated embodimentcomprises a return powder piston. Further embodiments of the presentinvention comprise alternative return powder devices that transfer aportion of powder from one side of the powder distribution device to theother side of the powder distribution device in preparation for thesecond pass of the roller or other powder distributing device. The laserpower measurement device 34 is also shown in FIG. 2 and is positionedbetween (along the z-axis) the laser window 36 and the heaters 38.

Certain embodiments of the present invention use the dual APL techniqueto distribute sinterable powder in layers. Dual APL is the process ofmoving the roller across the part bed 31 two times for each layer ofpowder distributed on the part bed. Prior art systems typically used asingle pass of the roller or other powder distributing device, such as adoctor blade or a doctor blade like structure that holds powder anddeposits powder as it moves across the part bed. Such systems typicallyhave hoppers or supply powder pistons on both sides of the part bed,while other prior art systems have a single hopper but deposit powderfor a first layer with a first pass and for a second layer with a secondpass (by depositing powder atop the roller assembly (or other powderdistributing device) and dislodging the powder on the side of the partbed opposite the hopper). Still other prior art systems use a singlepass of the roller or other powder distributing device to apply powderlayer in the single pass and then simply return the powder distributingdevice to its original position without applying a powder layer duringthe return movement because no powder is provided on the leading edge inthe direction of the return. However, as noted below and in the encloseddocuments, using the two pass dual APL process that applies powder inboth the first and second passes, it has been discovered that the powderdensity is significantly improved, as well as quality of the surface ofthe powder layer applied. The density of the powder in the powder layeris important because it has been discovered that the heating and lasersintering of the denser powder is more stable as the fluence (flow) ofthe temporarily melted material is better controlled during lasersintering. The improved density of the layers provided by dual APLenables used powders to be used for many more build processes becauseeven though the powder quality slightly degrades with each build processit undergoes, the used powder still can create parts with satisfactorypart quality (for example, surface quality is smooth compared to priorart techniques where reused powder can lead to rough surfaces such asthe well-known “orange peel” if too much powder is used too many times)and satisfactory strength. Therefore, the higher density powder layersprovided by the dual APL process significantly reduce the amount of usedsinterable powder that must be discarded, thus reducing the costsassociated with laser sintering while providing parts of better qualityand strength.

The dual APL technique comprises the following general steps:

-   -   1) powder is deposited from the hopper 20 (via chute 28) to        between the roller 26 and the part bed 31;    -   2) the roller moves across the part bed to distribute the        initial layer of powder over the part bed;    -   3) the return powder device 32 is in a lowered position such        that as the roller moves over the return powder device, any        powder remaining from the first pass over the part bed is        deposited into the gap created by the return powder device, such        that the roller moves over the powder above the return powder        device;    -   4) the return powder device raises so that the powder above the        return powder device is between the roller and the part bed;    -   5) the roller moves across the part bed to distribute the        remaining powder into any gaps, voids, or other portions missing        powder, to level any waves or other raised portions of powder,        and to increase the density of the powder layer; and    -   6) the roller is returned to its home position (show in FIG. 2)        while the laser scanning step occurs.

The dual APL is distinguishable from prior art techniques because itcomprises two passes of distributing powder, which is not obviousbecause two passes requires additional time for each layer, whichincreases the build time, relative to a prior art single pass system,for each part which reduces the throughput of a laser sintering systemif all other parameters are kept constant. Additional informationrelating to the powder density and part strength is provided in theenclosed documentation.

Turning now to FIGS. 3A-4B, certain embodiments of the present inventioncomprise a chute 28 positioned between the hopper 20 and the surfacebetween the roller home position (where the roller is positioned duringthe laser scanning operation) and the part bed so that a new supply ofpowder can be deposited in front of the roller before the roller's firstpass across the part bed. The chute of the illustrated embodimentscomprises a slot extending along the y-axis (front to back of thesystem) that is rotatable about an axis aligned along the y-axis. Thechute 28 may be rotated automatically or it may be moved by the motionof the roller, such as by contact with at least one pin 40 positioned onthe roller assembly 42 that moves the roller 26. For example, the roller26 or other portion of the roller assembly 42 may push the chute fromthe down position in FIGS. 3A and 4A to the up position in FIGS. 3B and48 at the beginning of the first pass (first APL) across the part bed,and the pin 40 or other portion of the roller assembly may push thechute back to the down position at the end of the second pass (secondAPL) across the part bed such that the chute is always in the downposition when the roller is in the home position. The chute may bespring loaded or otherwise biased to remain in the up position unless itis held in the down position by the pin 40 or other portion of theroller assembly.

The chute 28 simply serves as a conduit to deposit powder released fromthe hopper near the roller in a manner that minimizes dusting or othercreation of airborne particles. The illustrated embodiment is a simpleslot, but further embodiments of the present invention includealternative chutes that likewise reduce the dusting, spreading, or otherundesirable movement of the deposited powder. The chute 28 alsocomprises a chute heater 44 that pre-heats the powder in the chute sothat the deposited powder is closer to the temperature the powder mustattain when it is spread on the part bed prior to the melting/fusing ofthe powder particles by the laser. By pre-heating the powder, the buildprocess time may be reduced. Moreover, the chute heater or other heaterin the area may be used to pre-heat the roller. The roller heater,whether it is the chute heater or other heater, of certain embodimentsmay keep the surface temperature of the roller at a desired level sothat the roller distributes the powder in the desired manner. While theroller is in the home position during laser sintering of the powderlayers, the roller is slowly rotated (slewed) so that the roller surfaceis evenly heated. Further embodiments of the present invention includealternative roller heaters to heat the surface of the roller.

Turning now to the automatic laser calibration of certain embodiments ofthe present invention, FIGS. 5A-6C illustrate a laser power measurementdevice that can selectively determine the laser power (and energy)delivered to the layer of sinterable powder. Because the build chamberis hot and includes fumes and gases that may cause surfaces, such as thelaser window, to lose transparency, prior art systems have not measuredthe laser power within the build chamber but have instead measured thelaser power prior to (upstream of) the laser beam entering the buildchamber or measured the laser power during periodic servicing. Becausethe transparency of the laser window and the air within the buildchamber may change during a single build process, certain embodiments ofthe present invention measure the laser power within the build chamberperiodically during the build to determine changes in the laser power sothat the laser can be adjusted/calibrated to ensure that the powderlayers are receiving the desired amounts of energy (such as by changingthe laser power or changing the scanning speed that the laser beam ismoved across the powder layers).

The laser power measurement device 43 of the illustrated embodimentsincludes a laser power sensor of a type known in the art and atelescoping mirror 46 that may be selectively positioned in the laserpath to reflect the laser beam to the sensor for measurement purposes.As shown in FIG. 5A, the mirror 46 in the retracted position is outsidethe range of motion of the laser beam so that the laser powermeasurement device does not block the laser beam from the part bed. Asshown in FIG. 5B, the mirror 46 in the extended position is positionedwithin the range of motion of the laser beam, such as in the center, sothat the laser beam may be selectively projected to the sensor withinthe laser power measurement device 34. FIGS. 6A-6C illustrate oneembodiment of the laser power measurement device 43 in which the mirror46 is moved by a hollow telescoping shaft that is sealed about itsentrance into the build chamber 12. Further embodiments of the presentinvention include alternative laser power measurement devices formeasuring the power of the laser beam within the build chamber.

Because the heaters 38 are radiant heaters and it is not necessary ordesired that the laser power measurement device be heated and in orderto not block the radiated heat from heating the powder layers, thepresent invention has the laser power measurement device positionedabove the heaters near the laser window 36; however, further embodimentsof the present invention include the laser power measurement device atany location in the build chamber where the laser can be in opticalcommunication with the laser power measurement device.

The present invention also includes in certain embodiments a scrubber toclean and filter the air within the build chamber. FIGS. 7A-7Cillustrate a scrubber 22 in accordance with one embodiment, thatincludes an initial cooling section 48 and a filtration section 50. Thescrubber 22 includes a scrubber inlet 52 through which air is pulledfrom the build chamber 12 (such as from above the heaters 38 and belowthe laser window 36) and two scrubber outlets 54 through which air isexpelled back to the build chamber (such as into a heater bracket asdescribed below). The cooling section 48 is a serpentine passage orother structure that causes the relatively hot air from the buildchamber 12 to be cooled, such as with the use of a heat sink and fanassembly 56 in thermal communication with the passages in the coolingsection. The air is cooled to assist in the precipitation ofcontaminants from the air. The air is then passed through the filtersection 50 comprising one or more filters that capture the contaminantsfrom the air passing therethrough. The air is circulated through thescrubber 22 by the blower fan 58 rotated by the blower motor 60.

FIGS. 8 and 9 show the pipe or tubing that connects the build chamber tothe scrubber inlet 52, as well as one of the build chamber inlets 62 forthe return of the air from the scrubber. The build chamber inlets 62 arein flow communication with the respective heater bracket 64 in the buildchamber 12. The relatively cool air from the scrubber flows into theheater bracket 64 in order to transfer heat from the heater bracket 64and the heaters 38, thereby (i) assisting in the cooling of the heaters,which in some embodiments is desirable to increase the operable life ofthe heaters and/or to increase the performance of the heaters, and (ii)pre-heating returned scrubbed air. The pre-heated air passes out of thearray of holes on the side of each heater bracket 64. The array of holesare sized and positioned to minimize the amount of turbulence or otherundesirable air flow within the build chamber (for example, the powdershould not be moved by the air in the build chamber).

The enclosed documentation further describes the apparatus and processesof the present invention, as well as test results produced therefrom.For example, the chart entitled MP Data show the significantimprovements in mechanical properties relative to prior art techniques.The columns of the MP Data chart are for “Recycle Runs” where runs 1through 4 were conducted without adding any new powder to determine thedeterioration in part mechanical properties based upon the lack ofnew/fresh/virgin powder. The Recycle Runs were used to make a pluralityof ASTM638 bars for which the mechanical properties of Table 1 weretested for in accordance with industry standard practices known by thoseof skill in the art. The Recycle Runs included the respective amounts offresh (previously unused powder), overflow (powder previously used butretrieved from overflow reservoir and not the part cake), and part cake(powder previously used and retrieved from the part cake). The RecycleRuns were conducted with generally consistent build parameters and partparameters, including but not limited to a fill laser power of 60 W, afill scan count of 1, a fill scan speed of 12 M/sec, an outline laserpower of 15 W, an outline fill scan count of 1, a slicer fill scanspacing of 0.2 mm, and a sinter scan of 1. As evidenced by the resultsfor Runs 1, 2, and 4, the decreases in mean density, tensile modulus,and tensile strength are significantly improved compared to prior artlaser sintering apparatus and methods. Test data such as provided in theMP Data chart demonstrate that the embodiments of the present inventioncan be used to reduce the need for virgin powder and the correspondingneed to dispose of used powder.

TABLE 1 MP Data Mechanical Recycle Recycle Recycle Recycle RecycleProperties Run 0 Run 1 Run 2 Run 3 Run 4 Density (LT Front) 0.975 0.97109.67 (g/cc) Density (RT Front) 0.973 0.974 0.957 (g/cc) Density(Middle) 0.973 0.974 0.964 (g/cc) Density (LT Back) 0.973 0.968 0.964(g/cc) Density (RT Back) 0.971 0.974 0.957 (g/cc) MEAN DENSITY 0.9730.972 0.962 Tensile Modulus (X) 1911 1925 1798 Tensile Modulus (X) 18871948 1771 Tensile Modulus (X) 1878 1938 1845 Tensile Modulus (X) 19391917 1801 X MEAN MODULUS 1903.75 1932.00 1803.75 Tensile Modulus (Y)1962 1855 1904 Tensile Modulus (Y) 2012 1946 1893 Tensile Modulus (Y)1872 1897 1945 Tensile Modulus (Y) 1873 1861 1794 Y MEAN MODULUS 1929.751889.75 1884.00 Tensile Modulus (Z) 1924 2003 1761 Tensile Modulus (Z)1934 1879 2150 Tensile Modulus (Z) 1938 2003 1863 Tensile Modulus (Z)1915 1856 1879 Z MEAN MODULUS 1927.75 1935.25 1913.25 Tensile Strength(X) 50.4 49.5 48.9 Tensile Strength (X) 50.3 50.0 47.4 Tensile Strength(X) 49.7 49.7 49.4 Tensile Strength (X) 49.4 48.8 47.8 X MEAN STRENGTH50.0 49.5 48.4 Tensile Strength (Y) 50.4 48.6 48.6 Tensile Strength (Y)50.6 50.2 49.4 Tensile Strength (Y) 49.3 50.1 49.0 Tensile Strength (Y)49.0 48.5 47.7 Y MEAN STRENGTH 49.8 49.4 48.7 Tensile Strength (Z) 49.147.7 46.7 Tensile Strength (Z) 49.8 48.2 47.6 Tensile Strength (Z) 50.447.0 45.8 Tensile Strength (Z) 48.1 48.1 46.9 Z MEAN STRENGTH 49.4 47.846.8 Elongation at Break 18.137% 14.727% 19.061% (X) Elongation at Break18.975% 19.577% 17.212% (X) Elongation at Break 15.976% 20.259% 17.724%(X) Elongation at Break 14.579% 16.321% 22.901% (X) X MEAN EAB 16.917%17.716% 19.225% Elongation at Break 14.991% 14.734% 15.401% (Y)Elongation at Break 16.680% 16.386% 22.648% (Y) Elongation at Break13.161% 19.850% 24.640% (Y) Elongation at Break 17.391% 17.899% 16.648%(Y) Y MEAN EAB 15.556% 17.217% 19.834% Elongation at Break 8.324% 7.075%8.899% (Z) Elongation at Break 8.328% 6.926% 5.981% (Z) Elongation atBreak 9.280% 5.626% 5.724% (Z) Elongation at Break 6.944% 6.297% 7.321%(Z) Z MEAN EAB 8.219% 6.482% 6.981%

The present invention in various embodiments combines the aboveapparatus and methods to improve the part quality of laser sinteredparts and to improve the useful life of unused laser sinterable powders.Thus, the present invention provides significant technical and financialbenefits to users of laser sintering systems that were previouslyunavailable through prior art technologies.

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which theinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims. It isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

Accordingly, the present invention provides for the production ofthree-dimensional objects with improved build and support materials.Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which theinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims. It isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

That which is claimed:
 1. A laser sintering system for fabricating threedimensional objects based upon design data and from a sinterable powder,the laser sintering system comprising: a hopper for supplying thesinterable powder to a build chamber of the laser sintering system; apowder distribution device for distributing the sinterable powder in alayer on a part bed; and a chute extending from the hopper toward thesurface the sinterable powder is deposited upon, wherein the chute isbetween the powder distribution device and the part bed.
 2. A lasersintering system according to claim 1, wherein the chute is movable bymovement of the powder distribution device.
 3. A laser sintering systemaccording to claim 1, wherein the chute further comprises a chute heaterfor preheating sinterable powder within the chute.
 4. A laser sinteringsystem according to claim 1, wherein the chute is rotatable.
 5. A lasersintering system according to claim 1, wherein the powder distributiondevice comprises a counter-rotating roller.
 6. A laser sintering systemaccording to claim 5 further comprising a roller heater for heating asurface of the roller.
 7. A laser sintering system according to claim 1,wherein the powder distribution device includes a roller assembly with aportion adapted to move the chute when the powder distribution devicemoves.
 8. A laser sintering system according to claim 1 furthercomprising a laser power measurement device capable of measuring a laserbeam within the build chamber.
 9. A laser sintering system according toclaim 1 further comprising a scrubber and a heater bracket forsupporting at least one heater, wherein exhaust air from the scrubber issupplied to the build chamber through the heater bracket.
 10. A methodfor laser sintering a three dimensional objects based upon design dataand from a sinterable powder, the method comprising: depositingsinterable powder between a powder distribution device and a part bed,wherein the sinterable powder is deposited through a chute that isbetween the powder distribution device and the part bed; anddistributing the sinterable powder on the part bed to form a layer ofsinterable powder.
 11. A method according to claim 10, whereindepositing sinterable powder through the chute comprises heating thesinterable powder within the chute prior to depositing the sinterablepowder.
 12. A method according to claim 11, wherein the sinterablepowder is heated within the chute by a heater element on the chute. 13.A method according to claim 11, wherein the sinterable powder is heatedwithin the chute by radiant heat from radiant heaters.
 14. A methodaccording to claim 10 further comprising preheating the powderdistribution device with at least one heater element on the chute.
 15. Amethod according to claim 10, wherein distributing the sinterable powdercomprises moving the chute out of the way of the powder distributiondevice.
 16. A method according to claim 15 further comprising returningthe powder distribution device to a home position and moving the chuteto be between the powder distribution device and the part bed.